Insulated terminal for electrical apparatus



Dec. 14, 1926; 1,610,903

H. TRENCHAM TNSULATED TERMINAL Eon ELECTRICAL APPARATUS Filed July 29,1920 Invent or: Henry .Tend-lam byfw 4. M His Attorney Patented Deel 14,1926.

' UNITED STATES Pa'rrslvr4 OFFICE,

' HENRY TRENCAM, 0F RUISLIP, ENGLAND, ASSIGNOR T GENERAL ELECTRIC COM-PANY, A CORPORATION OF, NEW YORK.

InsuLA'rnD TERMINAL non nnncritrcan APPARATUS.

. Application filed July 29, 1929, Serial No. 399,944, and in GreatBritain January 3, 1920.

rial, such as a grounded metal casing, the.

casing being formed to receive the bush-1 ing. With such a recessedbushing or in-V sulator, it is well known that electrical dis- `chargesof afbrush or corona nature take place very easily from the edge of anyconductor carried therein, resulting in decreased safety and leadin todanger or' breakdown. 'lhe object of t is inventionv is to provide l animproved construction of insulated terminal device which will preventsuch discharges taking place, and to that end it consists in providing acombined metal sheath and bushing, the sheath being connected to atermnial within the bushing and placed so as to surround the terminaland project beyond it.

rlhe annular space contained between the terminal and the surroundingsheath is filled with insulating material so that the edges of thesheath are entirely embedded therein. As is well known, the vprovisionof such a sheath arrangedias described will relieve the inner termnial,of the electrical stress which l wouldotherwise produce the dischargereferred to, and will transfer such stress to the edge otthe sheath. Asthe edge ot this sheath is entirely' embedded in insulating material Vtothe exclusion of all air, nobrush or corona discharge can ltake place,and consequently no ionozation of the air in the neighborhood oftheterminal can occur.

The invention will bemore clearly understood by reference to theaccompanying drawing, the single figure of which shows a cross-sectionalview of my insulated termirial device. f

With reference to the drawing, l is an 1 insulator bodymounted in avgrounded metal casing 2,# which may be, for instance, a portion of atransformer casing.l Y i The' insulator comprises a body provided l witha. central bore 3, one end of which is expanded to form an enlargementor chamber 4. In the end of the insulator body opposite the enlargedportion of the bore, and concentric with the smaller portion thereof isa cavity 5 in which is located av metal sheath 6 electrically connectedas by conductive strips 7 vwith a conductor terminal 8 located in thesmaller end of the bore 43.

The metal sheath 6 preferably projects a little beyond the lower end ofthe terminal member 8, and is embedded in insulating material asillustrated, the space 5, in the rear of the insulator, being filledwith an 55 insulating compound, as shown.

ln installing my device, a conductor or cable from the transformer orother electrical apparatus within the main casing is secured bysoldering or otherwise to the termi- 7G nal 8 which may be detached fromthe remainder of the device while this is being done. 'lhe terminal 8 isthen brought into place within the bushing or insulator l and the strips7 bolted thereto, the strips Z serv- 75 ing to maintain the terminal inposition as well as to .connect it electrically with the sheath 6. Thespace 5 is then `filled with enough Vinsulating compound to cover thesheath 6, stripsy7 and the bolts and u per Bo end of the terminal 8,this compoun effectively preventing corona over theA surfaces of theconductive parts covered thereby. i

In the embodiment illustrated, the insulator is in one piece and shapedespecially 85 to allow for the required construction of the terminal andsheath, but it will be understood that the insulator may be built upfrom more than one part to facilitate manufacture and assembly, and thearrangement .90 may be modified in other ways without departing from thespirit of my invention, the scope ot which is set forth in the appendedclaim.

`What 'I claim as new and desire to secure 054 by Letters Patent of theUnited States, is

An insulated terminal device com rising an insulator body having acentral ore, va n metal casing surrounding said insulator body, aterminal mounted in one end of said' 100 bore, a conductor connected tothe outer end of said terminal, said insulator body having a cavityconcentric with said bore'and into said cavity and extending beyond theopen at the end of said insulator 'body outer end of said terminal toseal the s ace y in .which the terminal is mounted, a metal between saidconductor and the surounding l sheath located in said cavity andelectrically metal casing. connected to said terminal, said metal sheathIn witness whereof, I have" hereunto set Vsurrounding the inner end ofsaid terminal my hand this twelfth da of Jul 1920.

and insulating material sealing said sheath l HENR TRE CHAM.

